In cataract surgery, there has been widely performed a method in which an opacified lens is removed by means of phacoemulsification (PEA), followed by implanting the intraocular lens into an eye as a replacement for the crystalline lens thus removed. Such intraocular lens comprises an optical portion acting as a lens and a supporting portion that allows the intraocular lens to be held in the eye by positioning the intraocular lens on an eye axis. Further, the intraocular lenses broadly include a hard intraocular lens whose optical portion is made of a hard material such as polymethylmethacrylate or the like, and a soft intraocular lens whose optical portion is made of a soft material such as soft acrylic, silicone or the like.
The hard intraocular lens is inserted into the eye through an incision formed on the cornea or the sclera, which incision is as long as or longer than the diameter of the optical portion which is 6 mm. In contrast, the soft intraocular lens can be folded due to the flexibility thereof, thus making it possible to be inserted into the eye through an incision having a width of 4 mm or shorter, which width is shorter than the diameter of the optical portion. Further, insertion through a further smaller incision becomes possible when using a dedicated insertion device.
Narrowing the width of the incision reduces the burden imposed on a patient going through the surgery, and the possibility of corneal astigmatism caused by the surgery as well as incision infections. In this sense, the soft intraocular lens tends to be preferred.
An intraocular lens insertion device generally comprises an insertion device main body and an insertion tube. Such insertion tube has been used mainly in a disposable fashion in view of sanitation requirements. However, a type of insertion device that is disposable as a whole has been available, in which the insertion device main body and the insertion tube have a one-piece structure.
A type of disposable insertion tube that allows an operator or an assistant to place the intraocular lens thereinside at the time of operation is generally called a cartridge, and is made of synthetic resin such as polypropylene or the like. If the insertion tube is disposable, the insertion device main body is generally made of a metal and can be used for multiple times.
The operator injects into the cartridge an appropriate amount of a viscoelastic substance such as hyaluronic acid or the like, and then, places the intraocular lens in a lens placement section of the cartridge, followed by attaching to the insertion device main body the cartridge in which the intraocular lens has been placed. Then, the operator inserts through the aforementioned incision into an eye a nozzle section provided on an end of the cartridge, and releases the intraocular lens into an eyeball from a discharge port of the nozzle section by pushing the intraocular lens placed in the vicinity of a proximal end of the cartridge with an end of a plunger which is one of the components of the insertion device main body. In general, the lumen of the cartridge becomes narrower from the lens placement section provided on the proximal end of the cartridge toward an end of the nozzle section, thereby making it possible to fold the intraocular lens further smaller.
With regard to the cartridge, there has been disclosed, for example, an intraocular lens implantation device that allows the intraocular lens to be placed in the lumen of the cartridge in a folded fashion by first placing the intraocular lens in a placement section equipped with a hinge and then closing such hinge (e.g., see patent document 1). Further, there has also been disclosed an intraocular lens injector cartridge that allows an intraocular lens to be placed in an unfolded fashion through a lens insertion port of the cartridge (e.g., see patent document 2).
Furthermore, there has been disclosed an intraocular lens insertion device that allows the intraocular lens to be placed through the lens insertion port of the cartridge in a manner such that the intraocular lens is folded to some extent when being placed (e.g., see patent document 3).
In addition, from the perspective of a method of placing the intraocular lens, the structures of the cartridges disclosed in the patent document 2 and the patent document 3 are simpler than that of the cartridge disclosed in the patent document 1. Further, since the cartridges disclosed in the patent document 2 and the patent document 3 do not require folding by a hinge, the intraocular lens can be comparatively easily placed.